TMDL-How to fix Volney

5.6 Necessary Reductions

It is helpful to look at TMDLs in terms of reductions necessary to meet the standards. Watershed runoff phosphorus loads need to be reduced 62% overall, with reductions varying from 43% to 69% for individual watershed portions. The same reduction percentages apply to average export and concentrations (Table 5.6). The runoff TMDLs are based on requiring the same runoff concentration (183 μg/L) for each watershed portion.49

The atmospheric load is the only load that is not included in Table 5.6; all other loading, including the watershed load’s WLA portion, are represented. Internal load is zero due to Canfield-Bachman model incorporating as implicit in BATHTUB.